Before direct dust detections with ALMA, high-redshift studies routinely corrected the observed UV emission of distant galaxies for dust attenuation using the so-called `IRX-\(\beta \) ' relation between the ultraviolet spectral slope (\(\beta \) ) and the infrared excess (IRX, defined as the ratio of infrared to ultraviolet luminosity). Local starburst galaxies follow a tight relation in the IRX vs \(\beta \)  diagram [1]}, which can be explained if stars are behind a screen of dust with properties similar to those of dust in the Milky Way [2]}. Before the advent of ALMA, high-redshift galaxies were assumed to follow a similar relation. However, early ALMA follow-up of known Lyman-break galaxies (LBGs) at \(z>4\)  in Band 6 (\(\simeq 1\)  mm) found infrared luminosities that were lower than those predicted by the local starburst IRX-\(\beta \)  relation. This was found in a variety of targeted observations and stacks of \(z>4\)  LBGs (e.g., [3]}, [4]}, [5]}, [6]}, [7]}, [8]}): the lower IR excesses were more consistent with a steeper dust extinction curve similar, to the one observed in the Small Magellanic Cloud. Taken at face value, this result would imply that interstellar dust in EoR galaxies has fundamentally different properties than dust in low-redshift galaxies. This led to speculation that perhaps these galaxies have different dust properties due to their lower metallicities. This also implied that dust properties evolve rapidly in the early universe, since studies at \(z<4\)  seemed to show properties already consistent to Milky Way dust (e.g., [9]}). However, these results are plagued by the large uncertainty in measuring the total infrared luminosity of a galaxy from a single 1-mm ALMA measurement without knowing the dust temperature (see Fig. REF  and discussion in section 3.3 of [10]}).
